It is possible to make maps like this with a simple client-side source code modification that allows you to zoom out further in-game.
Simple meaning, simple if you're familiar with C++, compiling etc,...
As mentioned before, the actual technical details of how to do this can discussed on this forum, but please refrain from posting maps publicly on the internet. However, as far as I know, it is perfectly OK to make maps for private use and for use within your guild, as long as it is strictly limited to that.
If you want to know more about compiling planeshift, find the planeshift compiling guide.
[edit] Found it for you:
here [/edit]
Note that in the guide, no guidance is offered on how to modify the source, and what to modify. I don't think it's a good idea to publicly mention on this forum what you have to modify though, moreover, If you know how to do it, you'll probably be smart enough to not blindly share the maps with anyone out of respect for the community. You can always ask for help in the #planeshift-build channel on IRC (irc.freenode.net)
Also, please be aware that you are not allowed to connect to the public laanx server with a modified client. Please run a local test server for that purpose.